1. Field of the Invention
The present invention generally relates to an apparatus for constructing thermally insulated structures, such as walls, roofs, doors, shutters and the like, which utilizes an insulated core to thermally isolate front and back walls from one another.
2. Description of the Related Art
In the past, structures have been proposed which improve the insulating characteristics of a building, for instance, by installing improved shutters and doors. In one such system (U.S. Pat. No. 4,363,351), a shutter assembly is constructed with opposed wooden panel members forming front and back faces for the shutter. The panel members form an air void therebetween which includes a single sheet of insulating material sandwiched between thermally reflective layers. Within the air void, air gaps are formed between the thermally reflective layers and the outer paneling members to provide an overall thermally insulated shutter. An alternative shutter is provided (U.S. Pat. No. 4,115,953), in which a plurality of shutters close to form a dead air gap between an exterior of the window and an interior of the shutter. The shutters of the '953 patent are formed with an insulating interior layer, such as plastic or wood which is sandwiched between wooden front and back shutter faces.
An insulating door has also been proposed (U.S. Pat. No. 5,184,423), in which a rigid insulating layer, is formed between rigid wooden structural panels. The wooden structural panels are sandwiched between facing panels formed of a durable resilient material such as plastic. An alternative door has been constructed (U.S. Pat. No. 5,077,948) with wooden backing supports provided along the top, bottom and sides of the door. These backing supports surround the body of the door which is filled with foam. The foam body and wooden backing supports are surrounded by front and back half shells formed of a polymer composite material.
However, past doors and shutters offer limited insulating characteristics since, in the majority of the above-discussed systems, the interior and exterior walls directly contact or are formed integrally with one another. Also, the entire interior surface of the front and back panels contact the inner insulating material. Hence, these prior systems transfer a certain amount of energy between the front and back panels, and thus from the outside of the structure through the core materials directly to the inside. Similarly, these structures release heat from the interior through the wall to the exterior surface thereof through the surrounding periphery edge pieces for each door and shutter.
The shutter of the '351 patent uses air gaps between the wooden front and back panels. However, these air gaps are located immediately against the wooden panels. The wooden panels exhibit very limited insulating characteristics. Thus, the front and back air gaps would receive significant amounts of thermal energy from the adjoining front and back panels. The shutter of the '351 patent forms its primary insulating layer as a single layer between the air gaps. This single insulating layer would experience the same type of energy transfer through its interior between the dead air gaps as discussed above. Therefore, the configuration of the '351 patent does not offer an optimal insulating characteristic.
Further, conventional walls and roofs which include wooden studs experience the same kind of energy transfer as noted above. While these walls and roofs include insulation, the wooden studs directly contact the interior and exterior surfaces of each wall. Hence, the studs, and metal nails therein, transfer energy directly between the interior and exterior wall surfaces. Consequently, the resulting insulation factor of the wall is reduced below the stated R-value of the insulation within the wall and roof and floor panels.
Moreover, each of the above-discussed structures exhibit a limited life and limited security. More directly, the above-discussed prior art systems are only useful during the life span of the wood used therein. As the wood begins to rot and deteriorate, so does the integrity of the wall, roof, door or shutter. Also, doors and shutters constructed of wood only offer limited protection against burglars. Further, wooden structures, doors, shutters, etc. warp.
A need remains in the building industry to improve the insulating characteristics of structures and to overcome the drawbacks discussed above and heretofore experienced. The subject invention meets this need.